Rayleigh waves, surface disorder, and phonon localization in nanostructures

Maurer, Leon; Mei, S.; Knežević, I.

doi:10.1103/physrevb.94.045312

Cited by 23 publications

(15 citation statements)

References 113 publications

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“…Using Eq. (22), the thermal conductivity κ then has the universal dependence on the parameter zL/d = ζL where ζ is given in Eq. (16).…”

Section: Inset Ofmentioning

confidence: 99%

Universality of phonon transport in nanowires dominated by surface roughness

Markoš¹,

Muttalib²

2018

Phys. Rev. B

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We analyze, both theoretically and numerically, the temperature dependent thermal conductivity κ of two-dimensional nanowires with surface roughness. Although each sample is characterized by three independent parameters -the diameter (width) of the wire, the correlation length and strength of the surface corrugation -our theory predicts that there exists a universal regime where κ is a function of a single combination of all three model parameters. Numerical simulations of propagation of acoustic phonons across thin wires confirm this universality and predict a d 1/2 dependence of κ on the diameter d. arXiv:1802.03281v1 [cond-mat.dis-nn]

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“…Using Eq. (22), the thermal conductivity κ then has the universal dependence on the parameter zL/d = ζL where ζ is given in Eq. (16).…”

Section: Inset Ofmentioning

confidence: 99%

Universality of phonon transport in nanowires dominated by surface roughness

Markoš¹,

Muttalib²

2018

Phys. Rev. B

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“…More recently, Maznev [14] derived the specularity parameter for a rough surface with a finite Gaussian correlation length by solving the elastic wave equation for an isotropic medium and showed that Ziman's formula will likely overestimate the thermal resistance due to boundary scattering. Green's functions [15,16], molecular dynamics [17], and wave-packet simulations [18,19] have also been used to study the effect of surface roughness on phonon scattering at the boundaries of complex nanostructure geometries.…”

Section: Introductionmentioning

confidence: 99%

Spectrally Resolved Specular Reflections of Thermal Phonons from Atomically Rough Surfaces

2018

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The reflection of waves from rough surfaces is a fundamental process that plays a role in diverse fields such as optics, acoustics, and seismology. While a quantitative understanding of the reflection process has long been established for many types of waves, the precise manner in which thermal phonons of specific wavelengths reflect from atomically rough surfaces remains unclear owing to limited control over terahertzfrequency phonon generation and detection. Knowledge of these processes is critical for many applications, however, and is particularly important for recent attempts to create novel materials by coherently interfering thermal phonons. Here, we report measurements of a key property for these efforts, the phononwavelength-dependent specularity parameter, which describes the probability of specular reflections of thermal phonons at a surface. Our experiments show evidence of specular surface reflections of terahertz thermal phonons in our samples around room temperature and indicate a sensitivity of these reflections to surface imperfections on the scale of just 2-3 atomic planes. Our work demonstrates a general route to probe the microscopic interactions of thermal phonons with surfaces that are typically inaccessible with traditional experiments.

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“…We observe that an advantage of this algorithm is that it does not necessitate the direct calculation of the coefficients γ α,β and B α,β , but only requires the calculation of the nonadiabatic couplings d ij needed to evaluate the switching probabilities W ia and the adjustments ∆V i . We refer the reader to the extensive literature on the calculation of non-adiabatic couplings d ij ; e.g., for widely used independent particle formulations such as density functional theory, see [19,20] and references therein. That this algorithm achieves a numerical solution of the scheme (3)-(10) can be seen as follows.…”

Section: B Salient Propertiesmentioning

confidence: 99%

“…The assumption (20) of spatially localized atomic positions atomic positions allows one to approximateĤφ by the Taylor expansion,…”

Section: A Effective Hamiltonianmentioning

confidence: 99%

Nonadiabatic quantum molecular dynamics with detailed balance

Daligault

2018

Phys. Rev. B

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We present an approach for carrying out non-adiabatic molecular dynamics simulations of systems in which non-adiabatic transitions arise from the coupling between the classical atomic motions and a quasi-continuum of electronic quantum states. Such conditions occur in many research areas, including chemistry at metal surfaces, radiation damage of materials, and warm dense matter physics. The classical atomic motions are governed by stochastic Langevin-like equations, while the quantum electron dynamics is described by a master equation for the populations of the electronic states. These working equations are obtained from a first-principle derivation. Remarkably, unlike the widely used Ehrenfest and surface-hopping methods, the approach naturally satisfies the principle of detailed balance at equilibrium and, therefore, can describe the evolution to thermal equilibrium from an arbitrary initial state. A practical algorithm is cast in the form of the widely used fewest switches surface-hopping algorithm but with switching probabilities that are not specified ad-hoc like in the standard algorithm but are instead derived.

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Rayleigh waves, surface disorder, and phonon localization in nanostructures

Cited by 23 publications

References 113 publications

Universality of phonon transport in nanowires dominated by surface roughness

Universality of phonon transport in nanowires dominated by surface roughness

Spectrally Resolved Specular Reflections of Thermal Phonons from Atomically Rough Surfaces

Nonadiabatic quantum molecular dynamics with detailed balance

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